The long range goal is to study in detail the proteins involved in membrane cytoskeleton associations in normal and abnormal human erythrocyte membranes. The erythrocyte membrane is viewed as an experimentally accessible model system, which may have relevance to membranes of other, more complex cell types. The possibility of direct analogy between proteins of erythrocytes and other cells will be examined wherever possible. For the next five years, I propose the following projects: (1) Studies of the properties and function of human erythrocyte ankyrin and its reactive analogues which have been detected in other cells; (2) Purification and characterization of ankyrin-linked integral membrane proteins in human erythrocytes and other tissues; (3) Studies of human erythrocyte cytoskeletal proteins, with emphasis on elucidating interactions between individual proteins and of the factors that control assembly of these proteins into an extended structure. The possible role of the cytoskeleton as a matrix for organization of regulatory enzymes and their substrates also will be examined; (4) Purification, characterization, and determination of protein associations of heretofore uncharacterized human erythrocyte membrane proteins; (5) Studies of regulatory features of the human erythrocyte membrane, with emphasis on (a) the functional consequences of phosphorylation of spectrin, ankyrin, and band 3 (b) possible other post-translational modifications of membrane proteins of regulatory significance; (c) mechanism(s) of calcium-mediated effects; (6) Studies of membrane proteins from erythrocytes of patients with hereditary hemolytic anemias including hereditary spherocytosis, elliptocytosis, and stomatocytosis. Measurements will be made of spectrin-ankyrin and ankyrin-band 3 associations, and polymerization of cytoskeletal proteins from affected cells, with the goal of identification and characterization of abnormal proteins.